Accuracy of a semi-quantitative urine pregnancy test compared to serum beta-hCG measurement: a possible screening tool for ongoing pregnancy after medication abortion.

PURPOSE

Medication abortion protocols commonly rely on ultrasound or serum hCG measurement to confirm completion. In order to explore the use of a urine-based test to screen for ongoing pregnancy, we compared the diagnostic accuracy of a recently developed semi-quantitative urine pregnancy test to serum beta-hCG testing.

METHODS

We evaluated the urine test with 97 women in early pregnancy at a hospital and private clinic in Mexico City. The results of the urine test (hCG level > or <1000 IU/L) were correlated with those of a serum quantitative beta-hCG immunoradiometric assay.

RESULTS

The sensitivity of the urine test to identify individuals with a serum beta-hCG level >1000 IU/L was 88.6% (95% CI 74.6- 95.7%), and its specificity was 71.7% (95% CI 57.4-82.8%).

CONCLUSION

The reasonably high sensitivity of this urine test suggests it might be useful as a screening test to detect ongoing pregnancy after medication abortion. Future research should evaluate its utility in clinical follow-up protocols.